Switching apparatus for telephone exchange systems



J. ERICKSON ET Al..

SWITCHING APPARATUS FOR TELEPHONE EXCHANGE SYSTEMS June 1 1926.

Original Filed June 1 1926.

l J. ERICKSON Erm.

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o dit d JOHN ERICKSON AND CHARLES J'. ERCKSON, OF CHICAG, ILLINIS, ASSG-NORS, BY

MESNE ASSIGNMENTS, TO AUTOMATIC `CRPIMtTION OF DELAWARE.

ELECTRIC ENC., OF CHICAGO, ILLLlIOIES, .A

SWITCHING- APPARATUS FOR TELEPHONE-'EXCHANGE SYSTEMS.

Application iled October 16, 19GB, Serial No. 282,984. Renewed June 15, 1907.

Uur invent-lon relates to electrical ewitehilhziehinery und apparatus 'in general, l more portieulerly to the ewitehing mm ehinery mid ::i.. 13l1l'etusfs employed in :i1/nti .matie or semi-ltlitometie telephoixe systeme, und thrl'iugh the iloedmlii ol'A which the stili eeriliere melenithlee to eetehleh connection between their linee witl'iout the eseietohee oil switchboard opereeremor nt .leest to ne eol'nplieh the operntillm of e certain propel`- tion oil)A the exchange or ewitehhmtrd np perdite without the zie t mee oil ewitolr board operaltoreenal omeldlly to aulo-- inutile or eemi-ezlntonietie telephone sslly'ssteme olf thatelnzrsnfter in which the euheeriliore :Life provided fwlth ewitehing menne 'for 'trnnemitting one or more eleetriedl Ii11ipnleeeW-tte hy ihonientdi'ily grromiding either one r hoth lee ol: the line-flor cqpell'attlng one or more oleotifieevl-l pircnjielled stitch-- ing; iimeliihee :1t the o olminge or central station. .ln telephone eilte-lullige syeteinri olf t ehiilreeter, whether liutolmilie or only` toinetie, 'lte lf l iiilhle to provide 'the A with :l number olf' trunk-linee or other toimeetione which :1re oon'unol'i to Ill the eliheeifihere, or to ell the n'ieinhers; ol :L eerlziiii m1-oep olf :snlnetrlhere.` loreiizlinple, the en ehmm' unil online(- n oops o'l one hmnllfed sul ,rihere eer/h, :md :l'oi @mh gir-oni) oit :siilirlerihl-m; there may he :lllotll-ril ten trunk-lilies any one ol? which een he :well hy amy enhec.: wher in his group in l ahlal'lmgg; ooimfwtieii with eny other enlif rlher oa (the :time efzel'iiinge, or with :my .li-niheerlher ofls lilly other exehmige having t trlmlt-line eenheetlon with the enelhmgeto wllioh the sind group o? subscribers helonge. ll the enrhenge to which this:` group o'l euheeiriljiere holen le quite large, 1t muy he f l l fully s-seleet mi idle li'nnlclline from :t third growl), l'hue plfitting inlet three t1'unk-linee i lolo connection 'l'innlly eetithliehed direilly with the line oll the celled sulneoriliein e muy lle ol eoneiderehle Size y, :mtl nifty lie divided luto Serial No. 379,180.

ln eee-h eue-e, of cours-2, any idle trunk-line in the tiret, ol'onp will serve the purposes o'f the culling wlmeifilier, amd this is-trite of the eer.:\fn1 il amd third grolfipe, md o l the fonrtli und li'lth groups, il the exchange le very hlrge dnd includes e great number oil' sul),- eerilnzre. ln telephone Systeme of this eherznfter which ere very smell, or 'which are ol? considerable slee and operated only on e Semifautonietie heele, itin-ay then become nece .ry vl'or eheh eixlling snil'leeriher to milo omtiecn/ l-ly select only one trunl'eline, or other eli'i'iiler eol'ineetion, hel'ore the operation oe eure hy wlfiieh the final oonneetion is esteblllfleil directly with the culled. eubeeribefe line; hut in any event, and regerdl-ess olf xivhether the exehenge le large or smell, or automatic or semi-automatic in eharneter, tit is (leeirelile that the central Station or er 'lange epljmralnie he eo eolielruloted und zl-rrni'igetl `thiit fury calling); enhseriher will nel; ierily mid miton'ieticiit :y eeleet et least one idle trimlvline, or other eigiitnhle idle efr-nunon Connection, helore eonneetion ie `inrllly eletuhl-iehed with the line olE the called Subscriber; 'lor with euch arrimgemel'it, the 'idling edoserher actually operates or conlltrole either :ill or :l libert ot' `the nieehinery or :Lpperriltne hy whieh hie line le connected zh the lineol the celled Snlieeriher, thus d'iepeneing with either kell or it certain proi ortioo oiE the denial ewitehlioeVd o1; ereliorr3, and ninterlzllly reducing; the time in hit-l1 the milling sisi'ihseriher either ohllil thelleeired connection or rele :L eieinill imlitzfitihg tl nl' the celled sfinherrihefe line L' l l ln :in itlillonmtie lelephone twitching machine which pio eeloete the celled enheerihe1,"e line und .mu/kes Coiineetion directly therewith h; ommnonly lmown ee :it eonneetorlg :ind i'l the ell.- chnnge le large onfmgh to reduire it, these emmeetore are then arrm'iggj'e/Ql in grroiipi; und employed on :t percentil@J --thi\,t ie to my, they cam he divided into grol'ipe of ten, and enoli group ol Conneetore` l een be allotted, to :L group ol one lmrnlred euh siffrihere. In eheh ease, it illeeirahle to provide other s\\\'il:ehi:ng; machines which :ire commonly liniwn, ne eeleetore, end 'which nre employed hy enfllingengie rihers; in piek ing; out idle trmilt-lifnee. l'lthe exehmgu iis not `very largo, it will only lle nei-es ery lor each helling amlieeriherto izee'one se (lll lll)

lector and one connector in establishing connection With any called subseribers line; but if the exchange is larger, it may then become necessary tor any calling subscriber to operate a iirst-selector, then a second-selector, and nally a. connector, before establishing connection with the called subscribeis line. The iirst-sem lectors can each be allotted to a subscribers line, thus making the total number of first-selectors equal to the total number of subscribers in the exchange; then it second-selectors?.are necessary, these intermediate selectors v o-r switching machines can be employed on a percentage basis, thus, for example, making the total number'v of second-selectors only one` tenth of the total number of suliscribers; and'- it- Will be understood that these selectors are preferably divided into groups. In any event, a selector is preferably a switching machine of such character that it can be controlled bythe calling subscriber to the extent oi causing it to pick out any particular group of switching machines, either selectors or connectors, as the case may be, and which, after so doing, escapes momentarily trom the control ot the calling subscribe-r and proceeds automatically and by itself to pick out the lirst idle switching machine which it encounters in its operation, and which it finds in the group of switches selected by the calling subscriber. As distinguished from this, however, a connector is controlled by the calling subscriber throughout its operation of picking out and making connection With the called subscribers line, inasmuch as the calling subscriber must not only select a certain group subscribers lines, but must then cause the connector to select and make connection` with a certain one of such group of subscribers" lines. Take, 'for example, av system in which there are only first-selectors andy connectors, the. exchange being oi such size and capacity that second and third or other intermediate se lector-s are not necessary. In suc-h case,

the. tiret-selectors may be each allotted toy a single subscribers line, and the connectors may be arranged in groups and employed upon a basis ot ten per cent oi' the total number ot subscribers, so that there Will be only one-tenth as many connectors as the total number oi subscribersA lines entering the exchange. lith such arrangement, and calling subscriber will lirst operate his first-selector in suoli manner as to cause the same to pick out the particular group ot' connectors in which the called' subscribers line, terminates; but after this, and as it is immaterial which one oit these connectors is employed, the selector momentarily escapes troni the control of the calling subscriber and proceeds automatically and by itself to pick out the first idle trunk-line Which it encounters in its operation, and which it tinds in the group of trunk-lines running to the group ot connectors selected by the calling subscriber. After this, the calling subscriber then operates the selected connector in such manner as to cause it to select the parl` ticular group or division ot subscribers lines to which the called subscribers line belongs, and the connector is capable ot then resting in this position, or at this point, in its operation. Having thus caused the selected connector to pick out the desired group oi subscribers lines, the calling subscriber can then again operate the connector for the purpose of causing it to both select and make connection with the exact or particular subscribers line with Which connection is desired; thus, in a connector, the selection ot a group ot lines and the selection of a certain number oi such group are both definite in character. ln a selector, however, as explained, thc selection oi' any group of lines is always definite in character, but the selection ot any member ot such group is not definite, at least not in the sense that the calling subscriber Wants connection .vith a certain one of such lines and will not accept any other. In other words, the calling sub scriber must always select the exact or par ticular group of lines, Whether it be a group it be a group of trunk-lines or a group of subscribers lines, but is not called upon to select a certain line until after the selection has been made ot' the particular or desired group otl subscribers lines, and then, oit course, the selection from this group oi a certain subscribers line must be definite in character, as the calling subscriber Wants a certain subscribers line and no other. ln systems oi this character, and particularly in large exchanges, it has been found desir` able to reduce the tiret-selectors to a percentage basis, thus making the total number oi' first-selectors considerably less than the total number of subscribers lines entering the exchange. lith this arrange ment, both the selectors and connectors can be employed on an economical percentage basis. The connectors may be made common to all the subscribers, and the selectors may be divided iutogroups corresponding to the groups ot subscribers, the selectors ot eac-h group being common to all of the subscribers ot the group. Un` der such circumstances, it is customary to provide each subscribers line with what commonly known as an individualswitch that is to say, a comparatively simple and economical switching device by which a subscriber can automatically select an idle first-selector. For example, the subscribers lines can be arranged in groups of il D ill

ted subscriber may appropriate or close connection with any trunk-line selected by the said trunk-selecting means; the provision of a subscriber-s individual-switch ot such character that both the trunk-selecting and trunk-connecting means thereof may remain wherever they happen to be when the subscriber is through using his telephone, thus l'naking it unnecessary to restore the individual-switch to any so-called normal position, or to do anything more to said switch than simply cle-energize one or more of its electro-magnets or relays when the subscriber hangs up his receiver for the purpose ot disconnecting his line from the trunk-line which he was using; the provision of a subscribers individual-switch mechanism of such character that should its allotted subscriber cause it to close connection with the already selected trunk-line, and then for any reason tail immediately to begin calling the other subscriber, it will proceed immediately to advance and make connection with the next idle trunk-line it, in the meantime, some other subscriber calls in and makes a call and secures connection with the said already selected trunk-line, thus giving each subscriber the means whereby he may, at least under certain conditions, substitute an idle trunk-line for the trunk-line already connected with some other subscribers line; the provision ot' an improved construction and arrangement of subscribers individualswitches and a switch-operating machine common to all of said switches of such character that each individual-switch may, when put in use 'tor connective purposes, remain in operative connection with the said switchoperating machine, and whereby the trunkselecting means ot each individual-switch may, even while the switch is in use, remain subject to a selective operation each time another trunk-line is put in use; the provision oLt improved trunk-selecting machinery adapted for use in various connections, but adapted more particularly for use by telephone subscribers for automatically selecting an idle trunk-line or other connection preliminary to the final establishment of connection with the called subscribers line, and regardless of the manner in which such final connection is accomplished; the provision et a plurality ot trunk-lines or other suitable connections, together with trunk-selecting and connecting means ot such character that the mechanism is, when at rest, always mechanically set for the establishment ot connection with an idle trunk-line as soon as the trunk-connecting means is operated, and whereby the trunkconnecting` means when operated will always act in accordance with the condition at that time ot the trunk-selecting means, and will always ali'ord connection with the particular trunk-line which has been mechanically selected by the said trunk-selecting means; and thev provision ot certain details and features ot improvement tending to incrcasethe general elliciency and serviccability of automatic or semi-automatic telephone exchange apparatus ot this particular character.

To the foregoing and other useful ends. our invention consists in matters hereinafter set forth and claimed.

Fig. l is a diagran'nnatic representation ot one ot the sub-stations A comprised in our system and connected to its corresponding individua-l switching device C through the medium of the vertical and rotary line-conductors 2 and 8. To the right of said individual-switch is shown one of the lirstselectors D, with which said individual has temporarily connected the line of sub-station A. Below the individual-switch C is shown the individual-shaft controlliiig-apparatus E which belongs to the common shaft ot the group ot individuals oi" which the individual-switch C is a member. Again, to the right ot the tiret-selector7 l) is shown the connector-l F, which is one ot a group to which the subscrihers line has been extended by the selective operation of the Erst-selector D.

ln Fig. Q the individual-switeh H ot thc called line is similarly represented and is shown connected by the conductors land with the 'allcd sub-station J, designated as #220. Therefore, Figs. l and 2, taken together, illustrate the sub-station A connected with a second sub-station J through the medium ot one of the individual-switches C., the tiret-selector D, the connector F and the second individual-switch H, which last constitutes the terminal ot the linecondnctors that lead to the called substation J.

Fig. 3 similarly represents the mechanisms and circuits of the individu:1l-switch (l and the common controlling mechanism E, said individual switch beingl shown telnporarily connected with trunk-lines that lead to a first-selector D.

Fig. fl is a side elevation of the individualswitch supported upon an angle-iron base, showing the operating magnets and the individual-arm.

Fig. 5 is a detail view ot the line-relays by means of which the individual-switch C is controlled, said relays being mounted upon a supporting-plate.

Fig. 6 shows the switching and bridge-cut` oliA relays that control certain internal circuits in the individual-switchl and which are mounted upon the same plate with the line-relays shown in Fig. 5.

Fig. 7 is a top view of the relay supporting bridge.

F 8 is a front view of the shaft-controlling mechanism comprising the clock-spring motor device, the automatic winding mechaqi Li (iii (l il 'titi grounded.

iii, looking); `to the ieit "eolien oi the clochon line hm@ in lilig'.

Fie'. i() ie a similari view ofi' the shafi't es-` cupeiifient niei'rluiniei'u tahoe on liue ,lil-1U in Figi'. 8, looking; to the iiii'ht.

,Figi 11 is a` top view o.1 A ineehanienii and a privato-iV w 'i i eh tahoe p iu the rotation oi' the shaft to whit-h it le attached, both o1' 'which are instru mental in controlling; the rtjitation oi Said shafit, the one mechanically and the otlier eleetron'iagnetically.

lTig. 1231 is an end View et switch C. t

Fig. 13 :shows the iett eA ehat't eonunen to the `group oi indi. lduals to which individual C belongs, carrying cer tain detafiie among' which is the ciechi-Sprit] arrangement belong.;ing;` to the maid eh; i,

the i u di vidual wlfiieh epi-ing, being hebt cmispantly' wound automaticaily, maintains the el'iai't in rendi` nose ter instant i'uov'enient.

1315;'. 1-1 ehows a segment oi the autoufiatic 'winding device wlfiieh ie caused to be ener iii/.ed at each revolution oft'. 'the shaft, through the niediuni oi a lever attached to the Section oi' sliarit shown in Fig; i3.

Fig'. 15 shows the end ei said lever which Carr: a. Wedge for tripping certaiii devices hereinafter explained.

iig. 1G is a section through the sharit aud privateliel-:,` showing' the consti'urtion oft said pi yaterlislc and the acoohipagnyiai; wiper.

Fig. 1T is a diagranimatie poreneetive view oft" the .iirst-seiectoi" D.

liig. 18 is a siii'iilafr representation o'l the connecter F. i i 1 Although varioue|` batteries are represented, there :may be, however, but one battery 1% having' ni'e i`ieral; ly i positive pole The i1idividiutl--switeh is, as shown in the drawings, built upon a enitable' iraine 10 which is very clearly shown in Fig'. 11. Any suitable number oit these :individuals .may be mounted eide by side upon the saine support. Fig. 12 shows one oit the individuals in place upon an angle iron 11, and others may be piaceri on either side, with a shaft 12 common to all. The Ytraine 10 oit' the individual-ewiteh (l (Fig. 1) supports the relaydniidge 13, which latter is secured to the 'iiiirmer by holte` that pass through the holee 141. Upon thie bridge the individuallinerelaye 15 and 16, the switching-relay '17, and the bridge-eutotirelay 18, also sho'wii in Figs. 5 and (i, are attached by screws 1S) that pas-s through. `the holes 20. `Just below lthe bridge 13 the iehingonagnet 21 is attached. by the screw to an anglewpiece 22? (lig. it), said Maggio v o 'li the piece liieing seeured to the freine by the screws This lochinganagnet provided with an armature 25 that ie pivoted to a post 2G which rises from the `Walle of the switehliranie in juxtaposition to the poleqpiece oi the magnet 21, and its other or downwardly-` oxtei'iding encfl ie l'n'oric'ied with a notch, the object of which will hereinafter be fflieelosed. I'lziaid armature it; normally heid await' from the inagneifpoleqfiiece hy a retraeting---spring ill', one end ol which latter seemed to the lower end et said arniature, and the other end oi' which secured to the switching-:magnet Q1 and at right ai'iglee `to the aame, the release-magnet E28 ie secured by the screw 2i) to the angle-piece 2;)0, which latter is secured to the switcli-fralne by the ecrews 31. This magnet also is inovided with an armature 32 that serves as a lever oi? the third. class, and which pivotcd at its end eo ae to crees the armature ot the looking-magnet at approximately right angles. duet at `the point oi' crossing, the former arn'iature 32 has a eniall lug 55% against which the latter arnutture normally held by the retraetingspring 27. These two armatures are so adjusted that when the arn'uiture 32 is attracted `by the magnet 28, the notch at the end et the armature then falls over the said luggr 33 on the armature 32, thereby locking the latter against the pole-piece e1 the .magnet 2S, and away from the raelesegn'ient 10 carried on the wiper-carrier fil. This last armature 32 also ienorinally held away :from ite niagnet-pole-pieee by the retraetingspring 12, one end oi? which attaehetl to holds the' said members 11 and ifi so that one may move independently of the other under certain conditions. in other words, if the Wiper-carrier 411 ie ,loe-hed in one po- Sition in engagement with one particular bank-contact, and ii the ean'i 11G` is revolved by the shaft 12, the eaurdrag j11iwill be moved towards the outer extrei'nity oi said cam without disturbing the position oi the wiper-carrier L11, and, oit course, leavingtho arm as a whole no longer straigl'it. `Ou the switch-iliranie, ust to the right of the eamdrag 114, there is al ratchetfeatel'i 11T whieh. is pivoted near its rear end to e screw it. Said ratehet, by tirannie et' the ietrs'iotineyf The end oi this armature spring 49, one end of which latter is fastened to theY switch-frame, the other end lto a lug in the rear of said ratchet, is kept normally against the stopepin 50. Furthermore, said ratchet has loosely secured to it at its front end a light pin 51 which passes loosely through an opening in the armature 32. Said pin is provided on the end beyond thev armature with a head 52, so that when the armature is attracted by' the release-magnet 28, the ratchet 47 also is then drawn down. It should be understood that the pin 51 is not tightly associated with said armature. On the cani-drag 44 there is located a pin 53 which is, when the cam rotates and the cam-drag is driven out to the limit of the saine, caught by the ratchet 47, at which time said drag 44 is locked. Being once locked in said position, it is evident that the cam may continue to rotate, but it will no longer be encunibered with the friction of said drag upon its surface. Assuming the wipercarrier 41 to be in the position indicated in full lines (Fig. 4), and the cam-drag to be locked by the ratchet 47, as indicated by the dotted lines, if the armature 32 be attracted by the release-magnet 28, the ratchet 47 through the medium of the pin 51 will be drawn to a position indicated by the dotted lines, and the drag 44 will be permitted to fall to the position shown in full lines. The means that tend to restore the individual-arm to a straightened position consist of two springs 44a and 54. The ends of the latterv are held by the pins 55 and 56, the body of said spring being coiled beneath the head of the screw 45, as very clearly shown in Fig. 12. Of course, it is through the medium of the armature 32 and rack-segment 40 that the wipers 57, '58 and 59 may be locked in any one position, there being a ratchet-tooth for each position that the wipers may assume. When the armature 32 is in its normal po- Sition the end 43 falls into the notches in the segment 40 and holds the wiper-carrier in, whatever position it is caught. lt was stated that if the release-magnet 23 were energized the release-armature 32 would be attracted and that the armature 25 through the medium of the lug 33 would lock said release-armature 32 against the pole-piece of the releaseanagnet. Under these conditions it is evident that the wiper-arm 41 and, therefore, the wipers 57, 58 and 59 'are free to move wherever taken by the cam 46; This is true, of course, by reason of the fact that the cam-drag 44 is driven to the rightof the cam, and the wiper-carrier 41 is bound to follow ywith the pin 60 resting against the cam-drag, because of the tension in the spring 54. The wiper-car-- rier can be locked again by energizing the locking-magnet 21, which latter will attract supported from the shelf 75.

the armature 25 and thereby remove the locking end from the lug 33, thus permitting the spring 42 to draw the armature 32 into engagement with the ratcheteteeth 40. Of course, it will be understood that the banlvcontacts shown at 6l. (Fig. 3) are comprised in a bank more clearly shown at 61 in Fig. 4. The cam 46, being attached to the shaft 12, is operated b v the same mechanism that controls the shaft. In Fig. 13 one end of the shatt 12 is shown as having secured to it the clock-spring device with a clock-spring 62 which furnishes motive power for rotating the shaft. A hub 63 that is rigidly secured to the shaft by the screw 65 carries a collar 64. A cup 66 lits rotatively over said hub and against said collar. This cup carries the spring 62, one end of which is secured to the huh and the other (the outer end) to the cup 66. A cover 67 is clamped over the cup and held against the hub 63 by the collar 68 which is fastened to the shaft by the screw l69. Said cover-holder does not interfere with the rotation of the cup upon the hub 63. As shown in Fig. S), the outer circumference of the cup 66 is provided with ratchet-teeth that are more clearly shown in Fig. 14. The coil-spring 62 is tightened by the rotation of said cup through the medium of the ratchet and pawl device controlled by the winding magnet 75, which latter is provided with an armature 76 that vibrates about an axis passing through the pivots 77 and which is supported upon a shelf 7 5a that extends between the supporting members Si() and 117 (Fig. 8). The armature of the winding-magnet is normally held away from the pole-piece of the winding-magnet by a spring 73, which latter is riveted to the lugr 79 that projects above said armature and to the rear thereof. Said spring may he regulated by a screw S0 with which it cngages and which is fastened to the 'traino 81 of the winding-magnet upon which the armature is pivoted. To prevent said armature froin being given too high an angle, a piece S2 is riveted to the upper part ot the armature, with one portion protruding to the rear and extending down so thatI when the armature reaches a certain height said protruding portion strikes the magnet-frame 81. Furthermorel` the armature carries an extended arm 33 at the end ot which there is provided a linger wlwhich is designed to engage with a set of circuitbreaking springs 85, 86 and 67 that are The object of this latter mechanism will be fully described. This extending arin supports near its center a pawl-piece 63 one end ot which is pivoted on said arm, and the other end of which engages with the ratchet-teeth on the surface of the clock-springcup 66. Said iti to the magnet-frame.

segments as `there are contacts in the individual-bank 61, and, therefore, as many as there are first-selectors, identilied with the group of individuals of which the individual C is a member. This private-disk worrs in conjunction with the escapement device thatwcomprises the escapementmagnet 116 which controls the position of the shaft. "lhis magnet shown clearly in Fig. 10. The shaft which passes through the supliorting-frame 117, which latter is fastened to the anlgle-frame 11, has attached to it a` star-wheel 118 which normally engages with .the armature 11) of the escapement-magnet 116. Said escapementmagnet is mounted upon an angle-piece 120 that is Vsecured to the frame 117. The escapement-armature is pivoted on the end of the esoapement-magnet-frame 121, and is normally kept away from the pole-piece of this magnet by a spring 122 which is riveted This spring exerts a pressure on the ratchet side of the escapement-armature, between the pivots 123 and the star-wheel 118. Each time the escapeme-nt-niagnet becomes energized, the hool; end 124; of the escape-ment-armature disengages from the star-wheel and permits the shaft to rotate in the direction indicated by the arrow. The segments of the private-dish are insulated from` each other, and a wiper 125, which is also attached to the shaft, slides over the` commutatorsegment as the shaft rotates. T his wiper is in electric connection with the metallic Ahub 126 which is also insulated from surrounding parts.y A brush 127, attached to the angle-iron support 128, is in constant Contact with the said metallic huby and, therefore, in constant electric connection with the wiper' 125. t is clear that the angled piece 1.28 is secured to the member 120. Said wiper 125 (Fig. 3) is shown connected with the segment L152-3, and both are comprised in the circuit which enerlgizes the escapement-niagnet. Of` course, as the shaft 12 rotates, the private-disli-wiper passes from one comendater-segment to another. In Fig. 8 a section of the magnetframe is shown cutaway to give a View of the escapement-magnet. ln front of this magnet the star-wheel is shown, and to the right of the star-wheel the private-diskwiper fastened to the shaft. Just at the right of the private-dish-wiper, and attached to the frame, is the private-disk through the center of which passes the shaft 12. Itis evident, then, referring to Fig. 10, that if the escaliement-magnet becomes energized for a very short period, the escapement-armature will be drawn down for an instant, drawing the pawl extremity of said armature out of engagement With the tooth of the star-Wheel with which it is shown engaged, permitting it to fall back immediately `and soon enough to engage the next spur of the star-wheel. The energizing of the escapement-magnet takes place through a circuit that includes the private-dish-wiper and any private-disksegment with which it is engaged. This energizing occurs only when the privatedisk-wiper meets a private-disk-segment with a guarding potential. One segment,

by being connected with such a potential,

permits the star-wheel to escape one notch, and two segments side by side thus guarded permit an escapement of two notches, etc.

The lirst-selector may be of a welllmown type. The lirst-selector of the general type shown in Patent No. 815,321, ganted March 13, 1906, to Keith, Erickson & Erickson. In Fig. 17 the shaft 150 is shown carrying the line-wipers 151 and 152 and the private-wiper 153. These wipers are insulated from each other and from the shaft itself. On the upper section of the shaft there is a set of circular or so-called -vertical-teeth 154, and another set 155 of longitudinal or so-called rotaryteeth, all on one piece 156 which is shrunk to the body of said shaft. The former teeth are comprised in the means by which the shaft is raised and locked, and the latter are included in the means by which the n shaft is rotated and retained in any rotated position. The circular teeth are traversed by a groove 157 designed to engage the end of the shaft-rest or dog 158 which supports the shaft whenever the latter is rotated. Just below the ratchetteeth-hub 15G, a cam-piece 159 is fitted to the shaft and held in position by the tightening screw 160, the cam-piece being of a split sleeve form. To the top of the switch a guide-pin 161 is screwed; said pin holds one end of a coiled spring 162, the other end of which is fastened to the shaft. rl"he spring is designed to give the shaft a return or back rotation, but the shaft is kept in normal rotary position by the stop or guide-arm 163 which, when the switch is not in use, is kept against the guidepin or normal-post by the tension in said coiled spring. rlhe guide-arm o1' normalpost 16o controls a contact-spring 164-. with respect to the contact-point 165, for purposes hereinafter set forth.

rthe switcli a whole directly operated through the medium of the liuc-rclays 17d and 171, so long as it has not trunked through to another switch. and being of the trrml-release type surrenders control of its operative parts to the switch to which it trunks. The line-relays control the operative parts through the. medium of the armatures 172 and 173 and the line-relaysprings 17-1, 175 and 176. VheneVer the vertical-lirie-relay is operated the verticalmagnet 180, which is composedof two coils shown is llt) 181 and 182, energized. The said inagnet is secured tothe switch-frame and has opposite its free ends the vertical-armature 183 pivotally secured to the switch-frame by means of the pivots 18a and 185. The said arinature vih-rates up and down, being,1 drawn up when the vei'tical-niagnet is energizefjl and restored when said magnet becomes dcenergized by the retracting-spring 186 which is lined to the vertical-arm bye-ne end and by the other to the switch-frame. The vertical-armature carries a paw] 187 on its end, said pawl being heldin normal position by a small retracting-swing 1.88, which latter has one end secured to the verticalarni 189 and the other to the rear end of said pawl. This pawl is slotted-between its pivot flanges, and through said slot the end of the vertical-aun protrudes. Said slot is short enough to prevent the retracting-spring 188 from drawing the upper end of the pawl too far in a forward direction. On its under side the vertical-arm carries an L-shaped piece 190 that cornes into use in unlocking; the switch at the firstvert-ieal impulse of the vert-ical-armature. The release-magnet 195 Iis shown with only one coil. This is done to simplify the drawing; but in practice the release-magnet, like the vertical-magnet, is composed of two coils. The armature 196 of this release-magnet, hnown as the release-armature, isy suspemled from the switch-frame by the pivot-points 197 and 198 that afford said al1-mature the means whereby .it may vibrate about a horizontal. axis that passes 'through said points. Said armature is under control of the retracting-spring;r 199 which normally keeps it away from the release-magriet. `The ttor-- ward end of the link 200 broadens out and has a square aperture 201 which designed to engage with the so-called double-dog 202. rlaid double-dog supported in a 4vertical plane from the switch-frame by inf-2ans of the pivot-pieces 208 and has in its front part two angled arms 204- and 205 which, in the order named, act as locking-dogs for the shaft and work in conjunction with. the respective circular' and longitudinal teeth 1511 and 155. When in use the locking-dogs are kept against the shaft by the retractingspring' 169. The lower section ofl the double-dog consists of an arm 20G which projects downwardly and which meshes with the link 235 to aid inthe restoration of the `side-envitch after it has been used.` On its thi-i shaft-teeth by the pull of the releasearmature retracting-spring 199. lVhenever the vertical-magriet 180 is magnetized, the vertical-armature is attracted and the shaft is raised. At the first impulse of the vertical-armature the double-dog-linl; is raised und, disengaged from the double-clear. rit the same tii'ne the vertical-pawl 187 engages with one of the circular-teeth 154i and rar-es the shaft. l'Vhile the shaft Iis in this raised position, the double-dog, upon being freed from the controllingl` iirl'luence of the release-link, .moi-fes the dog, 201 under one ofthe circular teeth and thus insures there-- tcntion of the shaft in its new or raiseifl position.y As soon as i the ye. fical-ni:unict becomes (le-(energized. of course, the vertical-armature, due to the pull of the retracting-spring; 180, returns to its normal posi tion, but the shaft itself is caught and held by the arm 2011;, as d 4W hen the rotaifvline-relay is energized, the private-inaguet Q09 is thereby energized. This magnet is usually fastened lo a small priyate-niagmetframe that not shown and which is fastened to the main switch-frame. The prirate-mannet has an armature 210 that works in a viln'atory manner about a horinontal artis that passes through the supporting points 211 and 212. Said armature is formed with a forwardly-projeeting` arin 218, the latterhavingr two fiat s'mriiaces in au approxiinately horizontal plane. `Fur-- ther-more, the end of thei said arm isbent downwardly at right angles and carries certain. mechanical details, namely, a lateral arm 21.41- which isidcsigned to control the relation of the p ivato-springs 215, 916 and 217' and a tooth-escapement which includes two flexible springs 218 and 219, each of which is riveted by one and to the arm 21,8, one on thc upper side and the other on. the lower. The upper spring is straightand has formed on its end two tooth projections 220 and which extend down, while the former one is bent down and at right angles again to the front. This double angleon the lower spring is so designed that the latter may clear the bent portion of the privatearm against which portion said spring;r rests witl'r some degree of tension, and so that there may be space in front of said bent `portion `to receive two other tooth-shaped. upwardly-prejecting pieces 228 and 224 that are formed. on the forward end of the escapenient-spring, and` which are situated close to the upper' teeth but slightly to the rearward thereof. A; retraetingr--springir 225, which has one end attached to the privatearinature and the other end to the switchfran'le, holds said armature normally away from the private-magnot-pole-piece In conjunction with the escapement above descr hed, there is an .tpement-linger E230 which is in fact the right extreinty of the so--ealleffl siffle-ew lli-arm i231; Said flutter ist isnorinally retained behind the rearmost tooth of the lower escapement-spring. The side-switch-arm has nea-r the base of the escapement-iingcr a small lug 232 which is bent forward. The function of this lug is to control the stroke of the side-switcharni when it passes from the irst to the .second position, at which time it strikes the cam-piece 159. The side-switeh-arm may be made to oscillate about a pivotal support 233, llocated near its middle, and carries to the left of its center a rearwardly-projectingmember 234. which latter, on its eX- tremity, also carries pivotally secured thereto a link 235. The other end of said link is bifurcated and engages with the lower extremity of the downwardly-projecting arm 206 of the double-dog. Very near t-he left end of the side-switch-arm there rises perpendicularly a shaft 236 which supports the side-switch-wipers 237, 238, 239 and 240. These wipers are 'rigidl f secured to the sideswitch-arm and, as a whole. may be made to assume one of the three positions. In each of said positions each of these wipers engages one of a` series of contact-points 241, 242 or 24s; 244, 245 L0i 24e; 247, 24e 0i 249; 250, 251 or 252. The side-switch-arm with all its associated parts constitutes the well-known side-switch which, when in the first or normal position, retains the side-switch-wipers, in the order named, in engagement with the contact-points 241, 244, 247 and 250, respectively, and the escapement-inger 23() behind the tooth 223. In the second positionthese wipers, in the same order, are found in 'engagement with the contact-points 242, 245, 248 and 251, respectively, and the escapeinent-inger 230 behind the tooth 224; and when in the third posit-ion in engagement with the contact-points 243, 246, 249 and 252, respectively, and the finger 230 against the side-switeh-stop The force that operates the side-switch-arm 231, in a forward direct-ion, resides in a retractingspring 254, which latter is Jfastened by one end to the switch-frame. and by the other to the side-switch-arm. lVhen the privatemagnet is energized once, the private-armature is drawn down momentarily and restored. By this operation the escape'mentfinger230 passes iirst from behind the. tooth 223 onto the tooth 220, at the downward stroke of the private-armature, and from behind the'latter tooth at the return stroke. As soon as the escapement-tinger clears this last notch, the retracting-spring 254 draws the side-switch to the second position, and the latter is stopped by the lug 232 striking the cam 159. klhen the side-switch-wipers pass to the second position, in contact with contact-points 242, 245, 248 and 251, the rotary-magnet 260 is energized. this magnet 'comprising two coils 261 and 262.

' The rotating mechanism comprises the rotary-armature 263, a circuit-interruptingarm 264 that works in conjunction with two interrupter-springs 265 and 266, the rotaryarmature-linger 267 that exercises a certain control over the private-armature, and lastly the rotary-arm 26S. This rotary-arm carries pivotally attached to its ttor 'ard end the so-called rotary-pawl 26). Said pawl has attached to its rear end a small coiled spring 276 the other end of which latter is tar-tened to the rotary-arm, and which always restores the rotary-pawl to its normal position. At each rotary step of the shaft the lockingarin 205 falls into one ot the longitudinalteeth. Said locking-arm and longitudiinllteeth form the circular locking device. lhen the rotary-arniatalre is ei'iergized, the rotary-pawl 269 meshes with the longitudinal-teeth 155, and the shal't is rotated until the rotary-armature 263 strikes the rotaryinagnet-pole-pieces. The energizing-circuit of the rotary-magnet passes through the interrupter-springs 265 and 266, and when the rotary-armature is attracted they are separated by the interrupter-tinger 264. Then the energizing-circuit is lnoken, the rotary-armature is drawn tio its normal position by the rotary-arinature-retriutingspring 271.. Under the switch parts, and

v (L close to the line-wipers, the hne-ternnnalcontacts and the private-terminal-coutacts are shown in banks 272 and 273, respectively, one above the other. The private-(anitactterminals are each one electric comlucting piece; but the line-contact-terininals are each made of two metallic pieces, one over the other, and insulated from each other. lVhen the shaft is raised and rotated, the wipers engage with the contacts of their respective banks, the private-wiper with those ot the private-bank, and the line-wipers with those of the line-bank. A'l'ter the switch has been used it can be released-that is, restored to its normal position, hy the energizing ot' the release-magnet 195 by simultaneously energizing the line-relays 176 and 171, or by magnetizing the back-relcase-relay 274 that controls the back-releiuac-relaysprings 275 and 2T6. The circuits that are brought into play under these conditions will be described. Vlhen the release-urinature is drawn back, after the release-magnet loses its magnetizing torce, the double-doe is drawn away from the shalt 156. "he shalt, it it has been raised and rotated, rests on the sialt-rest 156 and, being: let't to the back pull of the coiled spring 162, it rotates on the shaft-rest until the stop-arm or normal post 163 strikes the guide or normalpost 161. rl`he shaft-rest then enters the channel 157 that traverses the circular teeth, and leaves the shaft to fall to its normal position by its own wei ght. When the Ishaft is raised, this normal-spring 164 closes with t-he contact-point 165, and in this way a lll) l Tl tl 

